Some conventional plasma generators, such as electrostatic thrusters, electromagnetic thrusters, and the like, operate almost exclusively on the noble gas Xenon (Xe). Xe is expensive and must be stored at high pressure in large cylindrically symmetric shaped high strength storage tanks which can compromise storage density.
Iodine is a halogen which is relatively reactive and much less expensive than xenon. Iodine can be stored at low pressure in smaller non-cylindrically symmetric shaped storage tanks. Iodine also has a higher thrust to power ratio than Xe at equivalent operating conditions. Iodine may also be collected at higher temperatures than Xe, making high power testing easier to accomplish. Thus, using Iodine as a propellant may increase storage density, improve performance, and reduce the cost of a plasma generator.
One conventional iodine electric propulsion thruster is disclosed in U.S. Pat. No. 6,609,363 to Dressler et al. As disclosed therein, iodine may be used as a propellant for Hall-effect thrusters and ion engines. The '363 patent relies on temperature controlled mass flow controller having a valve for flow control and shut-off to maintain a constant propellant flow rate. The '363 patent teaches the temperature controlled mass flow controller is maintained at the highest possible temperature. Thus, the '363 patent does not provide feedback to regulate the flow rate of the iodine gas to the thruster which may improve performance.